text:
Restricted Area "popping up" around you -- can it happen, and what do you do about it?
What happens if you are flying along through a Restricted Area (lets assume you're in a J-3 so you're VFR/no transponder, but you have a handheld radio to talk to ATC with) and  said restricted area is activated while you're still in it?  Would this be considered an operational failing on ATC's part, or would such a thing be blamed on the using agency (i.e. they ought to ask ATC "is anyone using this?" before they take it "hot")?  Are there procedures you should follow in this scenario, other than "fly out of the restricted airspace the fastest way possible and hope whatever hazard caused the R-area to go hot doesn't hit you?"

Isn't the pilot responsible to know about such activation before taking off, reading notams?

@mins -- some R-areas can be activated on "short notice"

Assuming your question is for the US airspace.

Short answer:
When the activation periods cannot be totally anticipated, the description of the area must reference the possibility of activation announced by NOTAM.
The NOTAM notice is normally not shorter than 4 hours before the activation.
While IFR flights will be prevented by ATC to enter or transit an active restricted area, non-controlled flights are under the sole responsibility of the pilot, as regard to flying within a restricted area.
A VFR pilot must take NOTAMs for restricted areas into account when preparing the flight (FSS), and should contact ATC when airborne for confirmation of the activation status.

From the pilot standpoint
You should not enter an inactive restricted area without contacting the controlling agency.
From AIM-3-4-3:

Penetration of restricted areas without authorization from the using
  or controlling agency may be extremely hazardous to the aircraft and
  its occupants

You are not allowed to enter an active restricted area without prior permission.
From the Federal Register, 14 CFR Part 73, §73.13:

No person may operate an aircraft within a restricted area between the
  designated altitudes and during the time of designation, unless he has
  the advance permission of (a) The using agency described in §73.15; or
  (b) The controlling agency described in §73.17.

FAA ATC, as the controlling agency, manages restricted area transit or avoidance, based on activation status, but only for IFR flights.
A pilot of a non-controlled flight (e.g. VFR) has the sole and complete responsibility for getting all information about the restrictions that may apply during its flight over a restricted area.
The briefing with FSS should include such research, contacting ATC prior to entering the restricted area seems the minimum.

From controlling / using agencies standpoint
A restricted area is part of the SUA (Special Use Airspace areas), and is jointly managed by Using and Controlling agencies.
Procedures for handling airspace matters, 21-2-4, Times of use:

a. The times of use indicate the period during which the using agency
  is authorized to schedule and use a SUA area. These times should
  reflect when normal operations are expected to occur. In determining
  the times of use, the proponent should select the minimum period
  needed to meet the using agency's requirements. The goal is to capture
  the majority of the day-to-day activities. When the using agency has a
  requirement for intermittent, less frequent use of the airspace
  (outside the specific published timeperiod), a provision to activate
  the airspace by NOTAM may be stated in the SUA legal description.

What does that say? If some periods of activation cannot be anticipated, the phrasing "by NOTAM" must be used.

NOTAM activation. Use "By NOTAM" or "Other Times by NOTAM" to
  indicate when a NOTAM must be issued in order to activate the area.

Regarding the notice prior to activation by NOTAM:

(e). NOTAMs should be issued as far in advance as feasible to ensure
  widest dissemination of the information to airspace users. Normally,
  the minimum advance notice should be at least 4 hours prior to the
  activation time.
NOTE-  Under no circumstances may SUA be activated by
  a NOTAM unless the words "By NOTAM" or "other times by NOTAM" are
  stated in the area's legal description.

A 4-hour notice is the minimum usually accepted for the publication of the NOTAM prior to activation of the restricted area. I assume the exceptions would be handled on a case by case  basis.
An area without a NOTAM mention cannot be activated outside of the published periods.
Example:
R-2305 Gila Bend, AZ
[...]
Time of designation 0700-2300 local time daily, other times by NOTAM.
Controlling agency FAA, Albuquerque ARTCC.
Using agency U.S. Air Force, 58th Fighter Wing, Luke AFB, AZ.

Related:

How to find out if Restricted Area is “hot” before taking off?
What should you do if you are forced to enter restricted or prohibited airspace?
Can gliders access restricted airspace?

It is extremely rare for an R-zone to be able to be activated by NOTAM with less than four hours' notice. Most R-zones in the U.S. are on a regular schedule printed on sectionals, with a few activated by NOTAM by the using agency with at least four hours' notice, and sometimes several days' notice is required by law for a few zones created along well-traveled Victor routes.
What's more common is an R-area that is activated, but "cold"; the hazardous or politically-important activity for which the R-zone was created and activated is not happening right now, and is not expected to begin happening in the time it will take you to traverse it. So, the using agency that controls the space while active lets you in and tells whomever is performing the activity requiring activation of the zone to hang loose until you're clear. While you're in the space, it should not be allowed to go hot; if the nature of the activity, or the communications between whomever's doing the activity requiring the R-zone and the using agency controller, is such that the using agency can't guarantee the zone stays cold, you won't be allowed to enter it in the first place.
A more common situation is a sudden "temporary flight restriction". These can be enacted by the FAA and similar agencies at a moment's notice almost anywhere they have jurisdiction, typically in response to an emergency situation. The airspace above a forest fire, for instance, can be declared off-limits within minutes of the fire being reported, as both a hazard to flight in several ways (hot, highly-turbulent, low-oxygen, low-visibility air for thousands of feet above a major burn) and to allow firefighting aircraft to do their job. Airspace within nominal distance of an area of law enforcement activity can be cleared in a similar way, officially in the interest of pilot safety in case of weapons discharge, but just as often the real reason is to get news choppers away from the scene to minimize the chances of someone being shot or otherwise spectacularly killed on live TV.
If an unplanned TFR is activated while you're in the airspace affected, you may not know about it until you land unless you're in contact with ATC or are intercepted by another aircraft and contacted on GUARD. The normal procedure would be to exit the airspace quickly and safely; this can be facilitated by ATC, who can vector non-participating aircraft to the nearest border of the TFR zone while maintaining separation.

Regarding law-enforcement-related airspace closures, another big reason would be in the interest of pilot safety by keeping news helicopters from running into each other or into police aircraft.

In my limited experience (MOAs only) the controlling agency—the center, usually, but could be an approach facility—will be the final in-the-moment arbiter of whether the using agency—the military—is allowed to actually take the airspace and make it hot, regardless of any prior coordination or NOTAM. If there is IFR traffic within the area they will not release it until that traffic is safely out of it. This release process involves the center controller coordinating with all nearby facilities whose airspace lies in or close to the area in question and asking their approval to make the area hot; any one of the surrounding controllers can deny the immediate release of the area.
Whether or not they would deny use of the area for a VFR guy would depend on the exact version of special-use airspace, whether the aircraft is receiving radar services or not, how easy it would be for them to exit the airspace, etc. At the very least, if you're on flight following and the airspace goes hot you can expect a heads-up call.


text:
What aircraft or airline differences would make the Sukhoi Superjet unsuitable for US regional airline operations?
What differences in the "stock" production SSJ-100 (as compared to CRJ-900s or EMB-190s), or in US regional airline operations (vs Interjet's success-so-far with the SSJ-100 in intra-Mexico and Mexico-to-US ops) would put the Sukhoi Superjet out of consideration for US regional airline operations?  Would post-sale support be the killer, or would the only thing in the way be the US government not liking it (either by the FAA shooting down the idea, or by way of an exorbitant trade tariff making it more expensive than other options)?

I have a suspicion this would be too speculative, when it comes to the governmental part of your question.

@SentryRaven -- an answer that says "it's wholly up to the USG whether they want to allow this or not" is fine by me :)

Your question is based on the assumption that it is in fact unsuitable. I guess you have some good reason for that, but if you could link to some background on why airlines, the government or whoever says it isn't suitable, that might help to get a better answer. Without that, you're really just asking for opinions.

@Pondlife -- basically, I'm asking because I don't know of a case where a US airline has purchased an aircraft built by a country outside the West, save for the various operators of the Embraers...

@UnrecognizedFallingObject Ah, that makes sense. But then why is your question so specific about the aircraft type? Maybe you could ask if there are any Western airlines who operate aircraft made elsewhere? That might be a more answerable question.

@Pondlife -- because it (to me) seems to be the most likely candidate for an acquisition -- it's not in competition with anything Boeing makes or really has made in the past while, the US favors RJs over regional turboprops, and it's already in Mexican airline service.

I would say sanctions would be the first issue. Sukhoi is one of the companies sanctioned by america due to it's involvement in Russian military industry . That means airlines in America wouldn't be able to purchase the plane in the first place (as long as the sanctions are in place). As for the technical side, the plane has been certified by EASA and various other international aviation authorities, so I would assume that the FAA would have a problem with that either.

Boeing worked with Sukhoi on the SSJ so it would be weird for them to then be anticompetitive about it... Or maybe it wouldn't. :)

@TaherElhouderi -- I didn't think about sanctions -- that'd be a good answer, at least for the time being.  (Of course, the situation's likely to change when Putin departs, but I'm not quite holding my breath for it either.)

The sanctions apparently were crafted not to affect the Superjet project or other non-defense-related aircraft production. The current sanctions in effect are also targeted at direct investment and sale of technology, not necessarily purchase of aircraft AFAICT

This is some speculation, but one potential reason is that U.S. carriers already have fleets of Embraer and Bombardier jets in this basic size (the Su-100 competes directly with the Embraer 190/195 and Bombardier's larger CRJs and upcoming C-series). The companies making these jets are located in pretty firmly U.S.-allied countries that are unlikely to see any economic restrictions that might hamper the ability of U.S. regional carriers to procure new airframes or parts.
The same cannot be said for Russia, which from 1946 until 1991 was pretty much embargoed by NATO signatories, and the relationship between Russia and the West since then has been testy. While the U.S. currently does not have a trade embargo with Russian civilian jet production operations (current sanctions attempt to specifically target military R&D and direct investment), that can change in a heartbeat if Russia continues to throw its weight around in neighboring countries.
Second, the seating capacity of this jet is a bit of an odd duck, as it blurs the line between the needs of regional vs. national U.S. carriers. The basic problem is that regionals, by their very nature, operate out of smaller cities with fewer potential passengers, at distances from major hubs that makes driving to that larger airport and flying from there more palatable for passengers. These considerations cause passenger count on regionals to drop off dramatically compared to longer "national" routes. The largest thing American Eagle currently flies is a Bombardier CRJ-900 (75 passengers in 2-class config), with the most commonly operated jet in AE's fleet being the Embraer ERJ145 (50 seats all-economy). By comparison the smallest plane operated under the full American badge is the A319 (124 seats in 2-class config).
There's an obvious gap between the two subsidiaries' aircraft capacities, but not much interest (by American at least) in filling it with a 100-seat jet like the SSJ100 (or E195 or C100). The primary reason is the collective bargaining agreements that pilots have with the airlines; they include, among other things, a requirement segregating the aircraft used by regional versus national subsidiaries. If you want to fly a plane with more than 80-100 seats (depending on exact terms of the agreement) on the route, you're paying a national airline flight crew the extra bucks to fly it; it's a violation of the CBA to put a 737 or A319 in the hands of a regional airline pilot because that takes the job away from the more senior pilots.
A secondary reason is that U.S. domestic airlines like American tend to favor more, smaller flights over fewer larger ones. This allows the airline to "rightsize" the route schedule (and its fleet) to passenger demand more closely and with fewer disruptions. If on a given day of the week, 200 passengers need to get between a regional airport and a larger hub, the airline could do that with four 50-place jets, or 3 75-place jets, or two 100-place jets. Theoretically, if demand were constant, it could save money the fewer flights it made, as the cost of the 50-seat Embraer's two-man flight crew would be roughly the same as the Sukhoi's, but with the Sukhoi you spread that cost over twice the passengers so your gross margin is higher.
However, an empty seat is a big fat goose-egg on the revenue for that seat for the flight, so if passenger demand varies (and it does, from day to day and seasonally), running larger jets either forces you to turn away some customers that you can't fit into the reduced schedule, or add flights that run mostly empty. Neither of these are palatable options for the airline; one pushes potential customers into the arms of their competitors, while the other has you running at least one flight that day costing tens of thousands of dollars for a handful of people with tickets whose regional component of the price might not even cover the pilot's salary for the duration of the flight (regionals are often "connecting" flights; DFW to PHX costs about \$320, ACT to DFW about \$300, but ACT to PHX via DFW only costs about \$360, so depending on how you part it out, the ACT-DFW leg of ACT-PHX might only really make you \$40 a seat, which might not break even if the plane's full, much less if it's half empty).
So, assuming any plane an airline would buy or lease is profitable when it's fully loaded with paying customers, American is more likely to successfully operate a route, and its entire network, using more smaller planes and scheduling a different number of interchangeable airframes and flight crews each day to maximize utilization, than it would be trying to also minimize the number of flights by using a variety of airframe sizes, which involves ensuring those airframes and the flight crews to run them are all in the right places at the right times (and deadheading - flying an empty plane from where it is right now to where it will be needed later - is bad no matter what the plane size, but typically more palatable with a smaller jet that has lower total operating costs).
Now, American isn't the only carrier with a regional subsidiary. US Airways Express and JetBlue, as well as several other New World regional carriers outside the U.S., regularly operate 100-seat Bombardier and Embraer airframes on regional connectors, and it would stand to reason that Sukhoi could get a piece of that action. It could also "stretch" the Superjet and try to compete in the national domestic market with the 125-seat A319 and 737-700 which are becoming more and more popular as U.S. domestic flights get "rightsized". However, the delicate nature of Russian-Western relations will probably continue to make Sukhoi a risky proposition for U.S. carriers that need a reliable source of airframes and parts on a 20-25 year timeline.

Nice analysis with a hat-tip to the geopolitical issues at hand.

Another economic factor for US airlines are "scope clauses" in their contracts with union employees, that might say, for instance, that only planes with fewer than 70 seats can be operated by the regional subsidiaries.  So the parent airline might have to operate the SSJ-100 itself as "mainline", instead of being able to farm it out to the regionals.  Since the airline's own "mainline" flight crews are typically paid much better than those at the regionals, this could make the SSJ-100 significantly more expensive to operate than it might otherwise be.

@NateEldredge -- yeah, there are some regionals that can't operate 90seaters due to scope clause issues, which is why I pitched it as an alternative specifically to the CRJ-900 and ERJ-190

The max seat size on regionals (e.g. American eagle) is typically restricted by the scope clause of the major carriers pilots CBA. If e.g American could put 100 seat jets in Eagle's hands, they would.

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text:
How do you convert true airspeed to indicated airspeed?
Is this something found in the POH? I know there is a IAS and CAS chart.

Did you perhaps mean the other way around: IAS to TAS? I'm not sure why you would want to calculate what your airspeed indicator is showing you directly.

This seems to be an odd question... You would normally do the calculation the other way round, since IAS is generally a known quantity and TAS is generally not. Of course, mathematically you can use the same formula to do the calculation either way.

Related, also by @User, possibly duplicate: How do you calculate indicated airspeed on a flight plan?.

@Pondlife Well I wanted to go from TAS to CAS to IAS, for planning my cross country.

I think this answer to the other question you asked covers this. Your POH usually lists a bunch of power settings and the TAS and fuel burn for each one. You pick the power setting (RPM) that gives you the range/performance you want, then you set the throttle to that setting in flight. Now you can read the IAS off the airspeed indicator and convert it to TAS, then compare your calculated TAS to the POH TAS. If there's a significant difference you can replan your time, fuel etc. You never need to calculate IAS because it's right in front of you.

Short Answer
Getting to grips with Aircraft Performance and Calibrated Airspeed are two good places to start!
The short answer:
From TAS to IAS $IAS=f(TAS)$:
$$IAS = a_0 \sqrt{5\left[\left(\frac{\frac{1}{2} \rho {TAS}^2}{P_0} + 1 \right)^{\frac{2}{7}}-1\right]} + K_i $$
From IAS to TAS $TAS=f(IAS)$:
$$TAS = \sqrt{\frac{2 P_0}{\rho}\left[\left(   \frac{ (\frac{IAS - K_i}{a_0})^2 + 1}{5}  \right)^{\frac{7}{2}} + 1 \right]} $$
WARNING: the units should be taken as SI, ($\frac{m}{s},\frac{kg}{m^3},Pa$).
In particular:

$a_0$: speed of soundat sea level in ISA condition = $290. 07 \; \frac{m}{s}$
$P_0$: static pressure at sea level in ISA condition = $1013.25 \; Pa$
$\rho$: density of the air in which you are flying $\frac{kg}{m^3}$
$IAS$: indicated Air Speed $\frac{m}{s}$
$K_i$: is a correction factor typical of your aircraft. You should find it in the POH.

How to get to this formula, see the long answer below.

Long Answer
From the definition of dynamic pressure:
$$ q_c  = \frac{1}{2} \rho v^2 $$
Where $v = TAS$, I am assuming you are interesting in subsonic speeds (cross-country flight), so we don't consider compressibility effects for the CAS:
$$CAS = a_0 \sqrt{5\left[\left(\frac{q_c}{P_0} + 1 \right)^{\frac{2}{7}}-1\right]} $$
Substituting the dynamic pressure definition in the $CAS$ as a function of $TAS$
$$CAS = a_0 \sqrt{5\left[\left(\frac{\frac{1}{2} \rho {TAS}^2}{P_0} + 1 \right)^{\frac{2}{7}}-1\right]} $$
Where $a_0$ is $295.070 \; \frac{m}{s}$ and  $P_0$ is $101325 \; Pa$. the density $\rho $ is the density at your altitude that day, you can get it from International Standard Atmosphere calculator or table/formulas.
If you measure it from your aircraft instruments $\rho = \frac{P}{RT}$, with $R=287.058 J kg ^{-1} K^{-1}$. You should give in Pressure in Pascal (not $hPa$) and most important temperature in Kelvin $K$.
Reverting the formula above (double proof is appreciated):
$$TAS = \sqrt{\frac{2 P_0}{\rho}\left[\left(   \frac{ (\frac{CAS}{a_0})^2 + 1}{5}  \right)^{\frac{7}{2}} + 1 \right]} $$
Being
$$
IAS = CAS  + K_i \\
CAS = IAS - K_i
$$
Where $K_i$ is a correction factor typical of your aircraft. You should find it in the POH.
Finally we get TAS as a function of IAS $TAS=f(IAS)$
So:
$$TAS = \sqrt{\frac{2 P_0}{\rho}\left[\left(   \frac{ (\frac{IAS - K_i}{a_0})^2 + 1}{5}  \right)^{\frac{7}{2}} + 1 \right]} $$

If my math is right (certainly no guarantee!) I think the derivation of the TAS formula is incorrect? In particular, the /5 should not divide the +1 (it should only divide the squared term), and the outermost +1 should be a -1.

I just dial in the OAT, look for the TAS in the white window, and read the IAS on the black scale.

Does that instrument have an aneroid cell built into it?

@quietflyer: I believe the knob at lower right is used to turn the pressure altitude to align with the OAT in the window at top center. I doubt it determines the pressure altitude itself.

Complementing GHB’s answer, an exact formula for converting CAS to TAS that takes compressibility effects, indicated altitude, and static air temperature into account is
$$
  \text{TAS}
= \sqrt{
       \frac{7 R T}{M}
       \left[
            \left(
                 \left( 1 - \frac{L h}{T_{0}} \right)^{- \frac{g M}{R L}}
                 \left[
                      \left( \frac{\text{CAS}^{2}}{5 a_{0}^{2}} + 1 \right)^{\frac{7}{2}}
                      - 1
                 \right]
                 + 1
            \right)^{\frac{2}{7}}
            - 1
       \right]
       }.
$$
In this formula (which is valid only for subsonic speeds), the inputs are

$ \text{CAS} $ — the calibrated airspeed ($ \text{m}/\text{s} $),
$ h $ — the indicated altitude ($ \text{m} $) up to $ 11,000 ~ \text{m} $,
$ T $ — the static air temperature ($ \text{K} $);

the output is

$ \text{TAS} $ — the true airspeed ($ \text{m}/\text{s} $);

and the various physical constants are

$ a_{0} = 340.3 ~ \text{m}/\text{s} $ is the speed of sound at sea level in the ISA,
$ g = 9.80665 ~ \text{m}/\text{s}^{2} $ is the standard acceleration due to gravity,
$ L = 0.0065 ~ \text{K}/\text{m} $ is the standard ISA temperature lapse rate,
$ M = 0.0289644 ~ \text{kg}/\text{mol} $ is the molar mass of dry air,
$ R = 8.3144598 ~ \text{J}/(\text{mol} \cdot \text{K}) $ is the universal gas constant,
$ T_{0} = 288.15 ~ \text{K} $ is the static air temperature at sea level in the ISA.

It's a common questions...you get a TAS from your POH based on an RPM setting in your cruise performance chart.  Some Navlogs have a TAS/IAS box.  If you can determine the IAS then you can look at the Air Speed Indicator to insure everything is correct (from an airspeed perspective).  You still need to do a ground speed check because the TAS/IAS question doesn't help you with Navigation and confirming the forecasted winds.  But this is a commonly asked question.
And yes, using your E6B and working backwards to your CAS and the chart in the POH for you IAS is how you do it.  It's faster with an electronic E6B for sure.
PS - thanks for the math above, which will be way more accurate than the E6B, but I doubt I'll be doing the math!  haha

You read your TAS from your POH. Then you get to your CAS by using a flight computer, such as the E6-B. Then you use your POH to convert from CAS to IAS.

This makes no sense.  Why would you ever start a calculation with TAS?

@Simon, well, that's what the question asks. So it should have been comment on the question rather than the answer.

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text:
Is there a service to review prior flight plans?
I was wondering if there is anyone that offers on-line searching of prior flight plans.

Do you mean your own, or other's flight plans?

My own would be just fine.

Lockheed Martic Flight Service has a function to see your own past filed flight plans, though I have no experience with it. I would presume that it would only show you flight plans you filed through LMFS.

I was looking for this function and was not able to find it a few days ago :(  If anyone knows how to get to it, this should provide everything I need as all of my plans are created and put through LM.

Lockheed Martin Flight Services (LMFS) provides a history of filed flight plans on their web site under Flight Planning & Briefing | History. The path to the particular page is: https://www.1800wxbrief.com/Website/showPilotHistory.
Unfortunately, only the last 15 days are available. So if your flight plan is older, it won't be displayed. Additionally, if you're filing your flight plans through a service provider that doesn't provide full LMFS integration (e.g., ForeFlight) it won't be displayed even if within 15 days. In this case, you'll need to refer to your service provider's interface.

Additionally, though this may not result in different data, LMSF offers a Recent Flight Plans drop down menu at the top left of the Briefings, Flight Plans, & NavLogs page, attempt at a direct link here.


text:
What should I wash my plane with?
What should I wash my airplane off with?  As a new aircraft owner, any help would be appreciated.
I am pretty sure using dish washing detergent is not the best here as we are told not to use the stuff on our cars.

If you want this question the be generic, good—it might be more helpful for others that way. But if you want specific advice for your aircraft, it would be helpful to know what your aircraft is; manufacturers recommendations will vary.

With already 8 positive votes for 56 views, we are obviously interested in the answer, but is there one which is not an opinion or a brand name?

Isn't prop wash doing it for you?

You should wash your aircraft in accordance with the manufacturer's instructions.
We could all offer opinions and product recommendations in response to this question. However, the best answer is: in accordance with the manufacturer's instructions. Since you ask the question generically, without any information on what aircraft you might have, I will answer generically.
Your manufacturer's instructions can generally be found in at least two places: the owner's manual/AFM and the maintenance manual. For example, in the owners manual for a 1975 Cessna 172M, you will find Section V: Care of The Airplane containing instructions on how to wash painted surfaces, bare aluminum surfaces, interior surfaces, and the windscreen and windows. The maintenance manual for the same aircraft contains nearly—if not exactly—identical information in chapter 2.
Now, for that aircraft and others, Cessna recommends use of mild detergent in certain applications; you might not find that overly helpful in choosing what to use. Based on my research and experience, and time honored practice that I've observed, Dawn dish soap is widely used for cleaning painted Cessna aircraft with no apparent long term harmful effects. The airframe that I fly for work has tens of thousands of hours on it, and while I cannot vouch for how often it was washed in the past, I try to wash parts of it a few times a week. There is no apparent washing damage to the paint.
I will also highlight Cessna's instruction to use Stoddard solvent on areas of stubborn oil or grease; this can be especially helpful in cleaning the belly with it's typical collection of oil and dirt. My practice is typically to wipe down the belly with solvent first, and then follow with a water and detergent wash.
If the manufacturer's instructions are not clear, or are otherwise insufficient to answer your question regarding your specific aircraft, I would recommend asking your maintenance professional. He or she should have both the knowledge and experience to steer you in the right direction.
For more insight into the world of aircraft cleaning, and especially for the specific product recommendations you want, you might take a look at this AvWeb article by Kim Santerre: Aircraft Cleaning.

Yes, I have taken a look at the POH however that is what brought me to ask the question.  I am not sure what the terms "mild soap" refer to?  What out there in the market would be considered a "mild soap"?  Should I throw on hand soap?  Vehicle soap?  Anyone have sucess with one soap aside from others?  Stickers popping off while using one brand over another?  Haze issues...ect.  If it helps I have a 1978 Piper Warrior II PA-28-161.  However it was repainted.  Does that affect the type of method or soap used?

BTW - I really do appreciate the advice.  Please don't take my last comment as a harsh one.  I was merely trying to clarify the need/validity of the question.

@Yogwhatup Certainly no offense taken. You give a lot of information in that first comment that would really specify and improve your question. As I said in my answer, Dawn would be my recommendation; be sure to read my third paragraph.

We'll go for it.  Thanks again.

Water and with little soap mixed in.  Don't get crazy with cleaning solutions.  I think I used just a little bit of Dawn.
DO NOT WASH YOUR PLANE TOO OFTEN AND AVOID PRESSURE WASHING!!  Too-frequent washing will cause water will to work its way into the wheel bearings and accelerate corrosion.
I washed mine a few times a year but dusted it frequently.  The only routine cleaning I did was bug removal.
I also gave the belly a once-over with Goop hand cleaner (no pumice, of course) and that worked magic on the exhaust, oil, grease, and hydraulic fluid stains.  I had to make a few passes but it was worth the effort.  The paint looked new!  Spot cleaning was simple after that.  Goop should be a staple on every hangar!
Use soap and water or plexiglass cleaner on windows and lense covers.  Never use windex or other harsh cleaners.  I used plexus to clean bugs from the wings as well.

What do you use / how do you clean bugs from the cowl/ leading edges?

There are specialty products for bugs but I think they're a waste of money. I used plexus most of the time. Spray, soak for a minute, wipe with a soft cloth, and repeat as necessary. Water would have worked but using plexus was easier.

Standard washing procedure should have no impact on the wheel bearings or other greased fittings. As you note, pressure washing is never an acceptable method.

@Pugz I use water, Dawn, and a nylon brush or soft scrubber to remove bugs. In the past, at another company, I used Zep with good results.

Wash it just as you would your car. Soap and water. Of course, be sure not to clog up static ports with anything.

What type of soap would you use?

Have a look at Extreme Simple Green. I have not used it myself, but apparently it is one of the best products you can use for cleaning a plane. Safe on aluminum.

Don't forget to wax it occasionally too, helps keep the bugs from sticking too hard to the leading edges. Take a lot of care with the windscreen, usually you want to use special aviation glass cleaner or just water and a soft cotton towel.

Alright - this is great info. As a simple add on what type of wax should I use?  I really am trying to avoid harming the aircraft in any way.

Automotive car wax like Turtle Wax or "Collinite Insulator" wax is what I've seen people use. Others swear by airplane wax like Aero Glaze.

This is potentially dangerous advice. Someone might wash a car with products that could be harmful to aluminum aircraft structure or the windscreen and windows. Washing should be accomplished in accordance with manufacturer instructions. And Simple Green can be potentially harmful to aircraft structures if used improperly.

Does the advice here also work with fabric aircraft? Our Piper Tri-pacer 135's fabric might not like the same cleaners as an aluminumininum one. :)


text:
On a sectional, is there a way to determine if an airport is an Air Force/Naval base?
On the east coast, we have a lot of Air Force/Naval bases that are listed on sectionals.  Is there a quick way to determine that an airport is one of these?

I thought that "AFB/AAF/NS" was a dead giveaway :P

@aeroalias Agreed - this answer for the question you referenced was the one I was looking for.  Shame there isn't a quick way to spot these out.  Of course due diligence is key in flight planning, during flight discussions it would be nice to be able to spot them quickly.

The answer is found here http://aviation.stackexchange.com/questions/7705/where-is-it-documented-an-airport-is-military As pointed out by aeroalias

yes, it is automatically shown on top of your post, there is no need of writing it again in the comments.

You are correct!  Thanks for pointing that out.

Credit should be provided for the source of the map e.g. Source: SkyVector to comply with the license terms.


text:
I need to clean my aircraft's windows - what do I use?
I need to clean my aircraft's windows what do I use?
Note: I hope this is not a "subjective" question, as I don't want to put a potential harmful substance on my aircraft's windows and as a new aircraft owner, I would think this would be a logical question.

I think the question should be reworded as "what is the procedure to clean aircraft's windows?" and details about the windows you want to clean should be added (material, aircraft model/type, dirt to wipe off,...).

I assume that your aircraft has acrylic windows. This is a very soft material which is easily scratched and cracks under stress. For cleaning, use these steps:

Rinse with lots of water to remove dust.
Wipe with a wet, soft sponge. Don't press on the sponge and move it in the direction of airflow. Moving the sponge sideways will increase the risk of sideways scratches which are caused by the movement of dirt particles over the acrylic surface. Those sideways scratches will impair vision when flying into the direction of a low sun.
Dry the surface with a chamois leather, again moving in flow direction.

Superficial scratches can be removed by polishing the surface with an acrylic or metal polish. Be careful with sandpaper because this could take off more material than necessary, resulting in optical distortions when looking through the polished area at an angle.
Never use alcohol or other organic solvents!

Great article here on the subject.
Most important bit of information is to rinse the windows thoroughly with water before touching them. Will rinse away any of the larger bits and pieces that will cause scratching of the window.
Also very important, is NOT using glass cleaner. Assuming here that you have acrylic windows, and the ammonia contained in most glass cleaners will cause crazing (very tiny cracks).
The best option for cleaning acrylic windows is actually your bare hand, and cleaning with a cotton rag (old t-shirt). The article linked above contains more of what not to get on your windows than it does of what to use, which is far more important in my opinion. A few bugs left on the windows is far better than a ruined window that requires replacing.
Hope that helps.

I agree completely about using a bucket of water first to knock away as much dust and grit first.  Also the advice to avoid typical glass cleaners since they will ruin plexiglass over time.  I used clean cotton towels and Meguiar's Mirror Glaze Clear Plastic Polish & Cleaner for over a decade of airplane ownership and the plexiglas looked as good as new always.


text:
Flightradar24.com track info
What is the meaning of the track info found on Flightradar24, as seen below?
Would be the angle between the route and the equator?

I don't think this is a duplicate - FR24 doesn't quite follow normal aviation 'practice'.

That is the angle between true north and the current ground track. FR24 is slightly different to (most) aviation in that it uses true north instead of magnetic north as the datum.

Track is the heading the aircraft is actually tracking over the earth's surface. This is different from the heading that the aircraft is flying, as wind does change the directional component over the earths surface.


text:
How is the fuel quality monitored/assured for jetliners?
With tens of thousands of flights daily, many out of smaller and perhaps 'sketchy' airports, it would seem that serious incidents caused by contaminated fuel should happen a lot more often (in a quick Google I only found two). Do commercial jets have some system whereby the airplane itself can verify fuel quality as it is loaded? Or do pilots & airlines rely entirely on the fuel supplier?

One over Colorado at altitude, restarted and did emergency landing in DEN. A second over Russia, flamed out on final and glided to a safe landing. I don't recall dates or carriers.

The most famous such incident is probably Cathay Pacific flight 780 in which fuel contamination jammed the fuel metering valves and prevented adjusting engine power.

@ymb thanks for the links, the first one sounds like a fuel filter problem and the second one is not conclusive, not clear either were actually bad fuel vs fuel system giving false indications.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
Why did the Beechcraft Starship use a delta wing?
From what i've seen delta wings are more appropriate to supersonic designs, and have poor lift/drag ratios at subsonic speeds. The Starship had a cruise speed of 300 kn, so what was the reasoning behind the wing design?
I know that the engine on the back/pusher configuration puts the CoG further back, so you would want to put the wings behind, but the Piaggio Avanti does the same with conventional wings.

On a side note, I like the Starship, and if anyone ever comes to see Jack Daniels in Tennessee, the closest airport, (KTHA) has a Beechcraft museum on the field with one of these.  During their slow season, my brother and I went there, and the museum staff let us walk up inside of it. The museum is called "The Staggerwing Museum."

Why do you think the Starship has a delta wing?

That’s not a delta wing.

Because it was something of a Burt Rutan trademark since his early days. His first designs, the VariViggen and VariEze, had such a wing already, and apparently he saw no reason to optimize the wing of the Starship.

Rutan VariEze in flight (picture source)
The only true innovation was a variable geometry canard, which he even patented. Being only 85% scale, the performance of the Starship prototype was formidable, but once the real production aircraft had been designed with full compliance to airworthiness regulations, the Beech Starship turned out to be less impressive. The additional wetted surface produced more friction drag. Piaggio's design is clearly superior.
By the way, the idea behind the variable geometry canard was sound: In the landing configuration it would balance the additional lift from the fowler flaps on the wing. But the whole mechanism cost more in weight than the reduction in drag during cruise could save.

Drawing from US Patent 4641800.

Thanks. So there's no advantage compared to the Piaggio. But for smaller planes, like the VariEze, is there a good reason for the delta wing, or is it just a quirk?

@Anonymous: The delta would help at high angle of attack, but you want the wing of a canard to stall first. So in principle such a wing has its advantages, but is the wrong choice for a canard configuration. Besides, the sweep makes it less effective and only helps to give the fins some more lever arm. But the cost for this lever arm is hard to justify. So, yes, it's more a quirk.

It's necessary to put the fuel tanks close to the cg of the aircraft so fuel burn doesn't significantly change the cg. This was done as a Delta in front of the main wing.


text:
Just how much power (as a percentage) is necessary to drive a compressor in a jet engine?
If i understand correctly this is the "back work ratio". I'd like to know how much % of the "gross" thrust is used by the turbine to drive the compressor in a typical turbofan.

Since you say turbofan, do you mean just the compressor, or both compressor and fan? Because in turbofan, most power is used to drive the fan.

Just the compressor, since the fan generates useful thrust.


text:
Runway distance remaining signs outside of USA and/or in meters?

Are there runway distance remaining signs used outside of the United States (and territories)?  From what I can tell by reading this document (p. 50), these are standardized by the FAA (§ 2-3-13), but not the ICAO.

Do these exist anywhere in SI units (e.g. meters)?

Image from ICAO document linked above

I can't really provide a thorough answer, but they certainly do exist outside the USA. Here is one example from Aalborg (EKYT): https://skraafoto.dataforsyningen.dk/?orientation=east&center=551831.34128862%2C6328221.655&item=2021_81_08_4_0022_00001695 Interestingly, they are spaced by 1000 ft (not SI units). I think it may be a military thing - EKYT is a NATO airbase

And an example from Madeira (LPMA). Don't know what the spacing is here. https://www.airliners.net/photo/LTU-Lufttransport-Unternehmen/Airbus-A330-322/1127098/L

There is no ICAO standard for runway distance remaining. Some nations have their own standards: for instance, Germany has a sign reading "½" in black on a yellow background at the halfway point.
This EASA document indicates that:

ICAO is currently working on the runway distance-remaining signs for which EASA is
following the developments and will review the outcome of ICAO's work.


text:
What are the unusually-enlarged wing sections on this P-38 Lightning?
Halfway through this video of the Lockheed P-38 Lightning, there's an unusual-looking example.  Notice the enlarged wing sections outboard of the engine bodies, and also how the cockpit fairing extends further aft than usual.
No other P-38 in that video has those features.
What were these devices (and their purpose)?
Also, what is all that gadgetry at the trailing edge of the port wing at its root (with respect to the port engine body), and also that L-shaped thing trailing behind?

It was a test bed that was looking into laminar flow on the wings.

was converted in 1942 as a two-seater, with an elongated central
  nacelle extending aft of the wing trailing edge, intended as a
  research vehicle to find ways of reducing drag, and was the only P-38
  to have have a full dual set of flight controls. Later it was modified
  with enlarged laminar-flow wing sections outboard of the engine booms,
  complete with slots and boundary layer control by means of exhaust
  bleed air.

There is some discussion on it here as well.


text:
How did the service ceiling certification change in the 70s?
According to this video (at 4:30-4:45) the "later" Cessna T337 and P337 were limited to 20,000 feet whereas the older models "had no such limitation - a quirk in changes in the certification standards that took place in the 1970s."
What were these standards changes, and why? Did this have something to do with concerns about hypoxia? (For the record, I DO know that pilots use supplemental oxygen at high altitudes in non-pressurized aircraft.)
I'm assuming this video refers to U.S. regulations (i.e. FAA), but are similar laws in place elsewhere in the World?
Also, I have already read this question - it appears the FAA regulation prohibits exceeding the certified ceiling only if the POH says so (according to @pondlife's answer). I did not know that...


text:
How are altimeter settings estimated?
So, I spotted another weird METAR from the same place that spawned the first one I asked about (it's a USAF base if you're wondering what kind of 'drome it is):

K... 060846Z 00000KT 10SM OVC002 18/18 A2995 RMK AO2A SLPNO ALSTG ESTMD $

While I can reckon that the barometric pressure sensor there's on the fritz (again) from the SLPNO and the $, they also have the "ALSTG ESTMD" remark on there.  While the estimate looks to be not too far out, or at least more reasonable than the completely bogus figure from last time, it raises a question: how are they estimating an altimeter setting in the absence of the AWOS's barometer?  Or does it just mean that their backup barometer isn't as good as the one on the AWOS, so the altimeter setting might be a few ULPs out?

One of the pre-flight checks is to make sure that your altimeter reads the same as field elevation. If you don’t know the altimeter setting, set your altimeter to field elevation and you get the altimeter setting.

@JScarry -- agreed, but I'm wondering how the folks who aren't sitting in front of an altimeter are doing it :)

The instrument they are using is not certified, hence the ESTMD.  When they get a certified one, the ESTMD will drop off the METAR.

@mongo -- make that an answer and I'll give you an upvote :)

@UnrecognizedFallingObject a better title might be, why are altimeter settings estimated.  The how is rather simple, they just use another instrument.  BTW, this is something that AFB tend to run into more than FAA facilities, from my experience. Perhaps the red tape has a different hue.

The instrument they are using is not certified, hence the ESTMD.  When they get a certified one, the ESTMD will drop off the METAR.
Technically, the primary certified instruments are inop or unavailable, so backup equipment, believed to be reliable, but not certified, is being used.


text:
On the V2533 engine, what protections do the FADECs provide against uncommanded unstow?
An uncommanded reverser unstow at high power is quite a problematic event for a flightcrew to handle, at minimum.  As a result, engine and airframe builders put protection mechanisms in to prevent this -- such as auto-restow functions, and on the CFM56-5, code in the FADEC that automatically rolls back the engine to idle upon detecting an uncommanded unstow.
However, I have not seen any documentation for the A320 family with IAE V2500 series engines that details what the FADECs on those engines do in case of an uncommanded unstow of the reversers.  (The A320 FCOM on Smartcockpit only covers the CFM56-5 equipped versions of the A320 family.)
Can anyone fill me in on this?


text:
In an aircraft with tab-flown control surfaces, how can a jammed surface be detected during preflight examinations or flight control checks?
Some aircraft use control surfaces that are driven indirectly through a flying tab system -- this is used to aerodynamically boost control forces, and works well enough in the normal case.  However, it is possible for such a system to mechanically fail in a way such that the flight control and the tab are both capable of free movement throughout the control range, but the control surface does not respond to the tab's movement correctly, causing a reduction or loss of control authority.
How can a pilot catch this type of failure in a preflight or during a flight control check? "Full and free" clearly isn't enough to catch such a failure, since the tab will move freely throughout the entire control range even if the actual surface is frozen in place.  Is it the case that the only way to catch this sort of failure is to disengage the gust locks and then try to move the control surfaces by hand through their full movement range?  Should the control surface position be fed back to cockpit instruments in these aircraft, or is that already a requirement/feature on such types?  Is it common practice or required in a "full and free" check to verify surface followup on such cockpit instruments when they are fitted?

At least for GA aircraft, I always move the control surfaces by hand and verify that 1) the opposite aileron moves in the opposite direction, and 2) the control column reflects proper movement. This also helps to remind me to remove the control lock, and I verify again during the "box check".

The system you describe was used on large aircraft before hydraulic actuation became standard. The proper name is servo or Flettner tab.
The preflight check would ideally have one mechanic move the cockpit controls and a second mechanic walk around the aircraft and command control movements. While the actual control surface would not move, the servo tab would, and the second mechanic would hold on to the tab to check if it does so against moderate resistance. Then he would manually move the control surface to check if it moves freely through the full deflection range. This might require climbing on a ladder for the second mechanic, but would be the only way to ensure proper function of the control system.
One pilot by himself would not be able to properly check the airplane.

Or borrowing the de-ice truck whistles innocently


text:
How do pilots make rudder inputs during negative G flight?
During negative 'G' flight, the forces on the pilot (or pilots) will tend to push their legs up and away from the rudder pedals on your airplane.  Needless to say, this is not conducive to making rudder pedal inputs!
Given that, if you are in negative 'G' flight in a suitable aircraft, and wish/need to make a rudder input during that negative 'G' maneuver, how do you do it?  Do military and acro aircraft use any sort of special mechanism (such as foot pedal straps) to help the pilots keep their feet on the pedals during negative-'G' regimes?

Just like when your car goes over a hilltop or speed bump a bit quickly, your muscles don't just "relax" and go limp, ragdoll-like... extending your leg will still extend it.

In an aerobatic aircraft (and I believe fighters as well), you are strapped in by a 5-point harness which is designed to keep your body in place. Otherwise, during knife-edge maneuvers the pilot would "naturally" support his weight by pulling the stick to the side :P

Yes, there are straps for the feet on some aerobatic airplanes. Normally, my legs rest on the instrument panel cutout anyway, so the straps make not much of a difference. Once, when one strap get entangled with the battery cable and I had to fly with substantial rudder deflection until shortly before landing did I wish those straps away.

@kevin -- yeah, but the 5 point harness can't stop the negative Gs from trying to force your legs into the bottom of the instrument panel...

Much like gravity doesn't pull your legs down during normal positive-G flight and force you to have constant pressure on the rudder pedals, the muscles in your legs can be used under negative-G situations as well. Go ride the Hollywood Tower of Terror © at DisneyWorld© and keep your arms against the seat when you drop. You'll find that you can do so with minimal effort, though it wouldn't be as much fun... ;)

@FreeMan -- the analogous case wouldn't be 1g flight (as our bodies don't have trouble with that) but actively pulling positive Gs...

@UnrecognizedFallingObject your question may be extended to any maneuvre where body geometry is harder to maintain.

The short answer is that at negative 2 G, the airframe limit for the A7-E, it took little effort to keep your feet on the rudder pedals.
In controlled flight there are aircraft limitations on both positive and negative G. I flew the A7-E for the US Navy and have some operational experience that might offer some context to the question.
I believe the positive G was limited to somewhere between 7-9 G. Can't quite remember the exact number, and it did depend on the external store configuration as well. Newer aircraft have higher G loading capabilities, although the human body has its own limit. Fitness and training can extend the pilots envelope to high G.
As mentioned negative G in the A7-E was limited to -2. There was no issue at these sorts of values keeping your feet on the rudder pedals. It is worth mentioning that the rudder is controlled by the AFCS (Automatic Flight Control System) system and so there is no real need to keep your feet on the pedals, although I did use them at times. Negative 2 G's was hard on the body, and a pilot would come back to the ship with bloodshot eyes after undergoing maneuvers that required this sort of thing.
I can think of 3 times that a pilot would find themselves in a negative G environment. I am not including standard acrobatic maneuvers, but more tactical situations. One, and this wasn't typical, was during training. At a high altitude you unloaded the aircraft to -2 G's and set a 45 degree dive. As the airspeed increased it entered an area on the IAS instrument that was no longer valid, and this was close to Mach. The goal was to observe the characteristics of the aircraft when it went supersonic. There was a gentle pitch down as you broke the sound barrier. I did this maneuver once, although I commonly practiced 45 degree dive bombing deliveries.
The second, and quite common, situation was a maneuver called a bug out. A bug out was used by a flight to engage other aircraft in air-to-air combat. It was at once a defensive and offensive maneuver. The lead called "Bug out. Bug out," and the flight went to -2 G's, unloading the aircraft, and giving up altitude for airspeed. As your adversary turned towards your 6-o'clock the flight would "Pitch back," and pulling positive G's, gaining altitude. Trading airspeed for altitude got the aircraft into slower flight where its turn rate could be maximized.
The bug out placed the aircraft immediately in free fall with military thrust applied. Rolling inverted and applying positive G's is like being in a turn in the sense that the positive G bleeds energy.
The third situation was a defensive maneuver. At low airspeed and with someone directly on your 6 o'clock the pilot might try to "jink." Jinking was a last ditch maneuver where the pilot randomly pulled maximum G, and then went full negative G. I used this against an F-14 in a fight, and afterwards the pilot came and told me he couldn't get a firing solution.
As for uncontrolled flight there is the flat spin which can exert substantial negative G on the pilot. If I remember correctly a flat spin had never been positively observed in an A7-E. It was postulated, however, that given asymmetric wing loading it might be possible. On the other hand the F-14 could enter a flat spin. Talking with pilots who had knowledge about this sort of flight I was told that the negative G could be large enough where it would not be possible to get your hands on the ejection handle, either low or high. Not sure about the feet :)
An interesting side note. At times a pilot will find themselves in a high g turn, grunting against the inflated g-suit, and fighting the encroaching tunnel vision. When I found myself here I would pull on the stick a bit more and watch my peripheral vision go dark (tunnel vision). A bit more g and the tunnel got even narrower, until it was like I was looking through a hole. Then I would ease the stick and watch the hole get bigger. Pull back and smaller. Kind of interesting.

Thanks for serving! That last paragraph... Interesting mindset that wants to push to the limit of passing out and potentially killing yourself just for the "interesting" experience of watching the tunnel vision come & go...

If you needed to descend quickly would it be preferable to roll inverted first so any negative g's would act like positive g's to pilot and airframe?

@TomMcW Are you referring to  using a Split S maneuver?

@KorvinStarmast I have no idea what it might be called. Haven't looked at different maneuvers. So I presume the two (negative g's upright vs positive g's inverted) have different uses in combat

I fly an aerobatic airplane.  My G meter goes to -5 and I've pegged it before.
My plane (& most aerobatic planes I've seen) don't have foot straps.
During a negative G maneuver, it's pretty easy to push on both pedals at the same time thus bracing your legs against any tendency for them to slide off.  It doesn't take much effort and I don't think about it while flying.

I believe the negative G limitation on the A7-E was due to issues arising with fuel and engine oil. Not positive about this statement. I know our allowed time in inverted flight was due to this. This said, it always amazed me that our negative G limit was 2, and there was a fairly short time allowed for inverted flight. Another interesting limit is the number of aileron rolls you could do in a row (3 or 5 I think). This was due to flight instabilities.


text:
What do "azimuth window" and "compass switch" refer to in this accident report?
I recently read the accident report on BEA 548, but I'm unsure of some technical terms used on p. 4 of the report (p. 14 of the linked PDF):

Apart from the probability that in the particular conditions he would
  have elected to handle the aircraft himself, an examination of the
  lamp filaments in the P1 'azimuth' window showed that at the time of
  the crash the compass switch was turned to port, thus indicating that
  P1 was flying.

My question is:  What are the "azimuth window" and "compass switch" in this context?  Was the HSA Trident equipped with some sort of flight control transfer system between the P1 (captain) and P2 (flight officer) seats?

They are autopilot controls are visible in this clip from the Wikipedia cockpit picture:

Source: Wikipedia
Airliner avionics have independent left and right systems for the captain and first officer. But, in many aircraft, there's only one autopilot. It's not a critical system and the crew can hand fly the plane.
The autopilot controls allow it to be set to receive data from either side. Standard procedure is for it to be set to the side of the pilot flying so it follows what the pilot flying sees. The pilot not flying can monitor the flight on their displays and detect any deviations.
Note the switch at bottom center with the option to select Port or Stbd.


text:
At what minimum height above terrain does a vertical structure need to be indicated on a sectional map?
I recently drove by what seemed like an unusually tall structure and used Google Maps satellite view, its distance measurement tool, and basic trigonometry to calculate that this building (some kind of grain silo at a poultry processing plant) was 175 feet tall above the ground.
But, it does not show up on the sectional map.  Other nearby structures, mostly 300-350 feet or greater, do indeed show on the map.
At what minimum height above terrain does a vertical structure need to be indicated on a sectional map?

I believe it is 200', but I'm not sure what regulation it is.

Refer to Aeronautical Chart Users Guide 2017. There are 351,148 obstacles in the database. Generally it is when ”a manmade obstacle is 200' above the highest terrain in the quadrant”. However, “in high density areas like city complexes, only the highest obstacle is represented on the chart”. Then they do the calculations below to show the obstacle on the chart.

I'll accept JScarry's answer, but here's a clearer image of the map shown in his/her image:

Courtesy of Skyvector.com.
P.S. I LOVE sectional maps - lots of interesting info there.

For some reason the Chart Users Guide is a scan of the pages in pdf form, not a real pdf. That’s why it’s hard to copy and paste. You can view a copiable version at https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/aero_guide/


text:
What are the layers of a pressurized fuselage (cross-section and construction)?
I've looked all over this site, and also Web searches - but I can't seem to find any discussion about, and the construction cross-section of, a commercial airliner's pressurized fuselage wall.  Not the cross-section of the whole cabin, but just the fuselage wall from inside the cabin to outside.
More specifically, I'm curious as to what layer (and where in the cross-section) contains the pressurized compartment.  Do the circular ribs (or whatever they're called) contain this layer, or is the outer skin the pressure vessel?
I've already seen the below questions (and their answers), but they deal primarily with cabin/cockpit window construction.

Why is there a hole in one of the layer of an airplane's windows?
Why do airplanes have curved windows?
What materials are plane windows made of?

The pressure hull is the aluminum tube formed by the outer skin and supporting frames which serve to stiffen it.  Within that is a layer of insulation which is fibreglass in a ripstop plastic material envelope made into custom fitted sections clipped into place, then the facia panels that create the interior surfaces.  At max pressure differential the hull swells a little bit, maybe a quarter inch in a large airliner.  The primary structure is the outer tube.
A big problem with airliners is warm and very humid interior air (from the passengers) is able to circulate between the facia panels and outer hull and some of this air gets between the insulation batts and the outer skin, which at altitude is really cold so the moisture condenses as frost/drops.  Over time water starts to get absorbed into the insulation.  Airliners can have hundreds of pounds of water in the insulation especially down at the bottom, and at heavy checks the insulation has to be removed and dried out.

Thank you for this answer, but after reading that second paragraph, I don't think I'll ever sit inside a pressurized aircraft the same way again knowing all that condensation is lurking in the insulation.  Ewww!!

It's worse in some airliners than others, and there are  aftermarket systems operators can install called "zonal dryers" that circulate low humidity air, which is the super dry air being pumped in from outside, between the insulation and the skin.

By "facia", do you mean "facial" or "fascia"?

Oops I guess it should be fascia.


text:
Why all the taxiway construction at PHL?
Perusing Google Earth around Philadelphia, I noticed some new taxiway construction at PHL/KPHL.  The "time machine" feature of GE shows this to be new (latest imagery data is May 2016)--the paved areas in the red circle below don't appear in past aerial imagery.
What are all these paved areas for?  Are they extending 10R/27L?

From Google Earth
Note:  The Google Maps image for this area shows an older aerial image (without all that extra concrete).

From the KPHL website

Realign Taxiway H and Establish Taxiway EE (North)
This is the first phase of a multi-phased project to provide a 1,494
  linear-foot extension of Runway 9R-27L, construction of associated
  eastside taxiways and hold pads.  In this phase a new Taxiway EE will
  establish a connection between Taxiways H and K and Taxiway H will be
  realigned between Taxiway EE and the existing Taxiway D.
Projected completion date: August 2016

As well as,

9R-27L Extension - Site Prep, Utility, & Fuel Line Relocation
This is the first phase of a multi-phased project to provide a 1,494
  linear-foot extension of Runway 9R-27L, construction of associated
  eastside taxiways and hold pads.  In this phase a new Taxiway EE will
  establish a connection between Taxiways H and K and Taxiway H will be
  realigned between Taxiway EE and the existing Taxiway D.
Projected completion date: October 2016

The imagery predates the projected completion dates so it makes sense.


text:
Aerodynamics of double winglets
I've read here on Aviation SE that the aerodynamics of winglets on an aircraft are easily described as "extending the airfoil".  Thus, as I understand it, a winglet is like stretching the airfoil a few feet and "bending" it upward.
Now, this answer mentions the various types of winglets used in contemporary aircraft, but I'm not sure the B737-800s I've seen (such as the one in the below image) with double winglets perfectly matches any of those categories1.

source
Thus, my question is:  How can one best describe the aerodynamics (and benefits) of the second, downward-pointing winglet in the context of airfoil extension?
1 I claim that the 737-MAX's "split scimitar" as mentioned in fooot's answer is different than the aftermarket double winglet seen in the United (Continental) B737-824 in the image.

They are the same split scimitar. United is retrofitting it's 738 fleet with them

Winglets don't have some mysterious magical wing tip extending property.  They don't add to the total lift of the wing (except to the extent they are canted).
The best way to conceptualize them is they extract energy from the tip flow and convert it to THRUST which can be deducted from the induced drag.  They are little wings making lift (wing..let, see?), except the lift isn't up (unless they are canted, where there is a small vertical lift component).  They work the way boat sails propel a boat forward and were originally called "tip sails".
The flow striking the winget on top is curling inboard toward the fuselage so that there is an outboard angle of attack at the winglet's leading edge that creates a lift vector (being 90 degrees to the local AOA) inboard and slightly forward.
The split scimitar doohicky just flips the effect over to take advantage of unexploited flow below and behind. The flow striking the winglet on the bottom is angling outboard, causing a lift vector to be applied outboard and slightly forward (again at 90 deg to the local AOA).
If you examine most winglets you will see that they aren't just fins that "block" the flow. They have an airfoil cross section because, as I said, they are wings making lift... just not up.
The benefit of the lift being created at the winglet is only sufficient to exceed the thrust and weight penalty of the winglet itself at lower indicated airspeeds where the vortices are stronger.  For this reason you (almost) only see them on high altitude aircraft that cruise at low indicated airspeeds.

… but they do add a little lift, because they raise the pressure difference at the (horizontal) tip from zero to some small value. And the flow hitting a properly designed winglet is pushed outward (like the downwash behind a wing).

Good point.  Actually I was thinking about downwash thing and was going to add something about the "outwash" generated by the winglet itself (of the upper one; "inwash" of the lower one) counteracting the circulation and that could be thought of equivalent of adding span, but I think the energy recovery of the lift generated by the winglet itself is the biggest factor and is the best thing to emphasize when describing them.  One of the few articles I ever saw that properly described winglets was a Peter Garrison article in FLYING mag in the 80s that used the boat sail analogy to great effect.

The boat sail analogy, the reduced lift vector tilt, the reduced downwash and the "outwash" explanations are only different ways to describe the same phenomenon.

A reasonably complex question.  What you see is call a Split Scimitar Winglet.  Lots of references online – see Wingtip device on wikipedia.  Simplest explanation: "Their intended effect is always to reduce an aircraft's drag by partial recovery of the tip vortex energy."
A better answer maybe that United believes that a cruise performance boost of 30-40% is worth the effort.

Thus, my question is: How can one best describe the aerodynamics (and benefits) of the second, downward-pointing winglet in the context of airfoil extension?

You can extend the wings many feet which reduces drag and also makes for a very ramp unfriendly airplane.  Winglets make wings behave as if they where longer.  Wingtip vortices are reduced with the one upward winglet the lower or downward scimitar tip reduces vortex loss even more.

30-40%? Where did you get that figure? It's usually more in the range of 2-3%

I should have sited the source, sorry.  I doubt that it is correct or at least far from context.  https://gizmodo.com/how-these-simple-scimitar-winglets-make-the-737-a-whole-837341873

2 - 3% seems low also.  The cost of modifying a fleet of 373-800s must have been high.  If all you get back is 2 percent, even if after the investment, hardly seems worth the trouble.  A few hundred million here, a few hundred million there, what do I know?


text:
Why were the 747SP's trailing-edge flaps so much different than those of the -100/-200?
I read several decades ago about how the 747SP's trailing edge flaps were substantially redesigned from those of the "original" 747-100/-200s.  The images on the 747SP Wikipedia page clearly show what appears to be an unslotted Fowler flap - contrast with the triple-slotted Fowler flap of the 747-100.
Why the major re-design?
Related sub-question:  The Wikipedia page also mentions "... the SP's heavy wings" as one of the factors contributing to its cancellation.  But, the SP had the same wing (modulo the trailing edge flaps) as the -100/-200.  How could its wing be considered "heavy" in this context?  (I'm thinking maybe it has to do with moments of inertia and/or size relative to the fuselage, but hopefully someone else here can clarify this.)

Wikimedia Commons (from the Wikipedia 747SP page)

The wing was relatively too big for the airplane after cutting bits of the fuselage off, which reduced weight by 11,000 lbs. The aircraft did not require the triple slotted high lift devices anymore: if the wing area is large enough the wing requires no flaps & slats but has relatively high cruise drag. All in all the total weight savings on the SP was 45,000 lbs. (Source)
The B747SP could not do completely without flaps, but the simpler flaps of the SP saved weight. The competition at the time was DC10 and L1011, which had lower wing area and one less engine, resulting in better fuel economy.

B747SP: 300,000 kg, wing area = 511 m$^2$, wing loading = 587 kg/m$^2$
L-1011: 231,000 kg, wing area = 320 m$^2$, wing loading = 722 kg/m$^2$
DC-10 : 263,100 kg, wing area = 368 m$^2$, wing loading = 715 kg/m$^2$
Source

In cruise, a smaller wing area means less resistance: higher wing loading gives better fuel economy, but creates problems at low speed which need to be solved with high-lift devices.

This was primarily done to reduce weight- Simplifying the mechanism resulted in significant weight savings. Also, I'm not sure why the wings were called 'heavy'. While the SP used the same wings as the legacy 747s, the internal structure and construction was modified significantly for weight savings. As this site notes:

While Boeing chose to retain the standard 747 wing on the SP the internal structure was significantly modified to reduce weight. To save weight Boeing employed reduced gauge metals in the wing spars, ribs, skin and stringers in the wing box and center fuselage sections.
In an effort to further reduce the weight of the wings engineers designed a single-slotted variable pivot flap system.  ... (which) ... removed 12,000 lbs in weight from the wing structure.

Considering the total weight savings was around 45,000 lbs, this is more than a quarter of it!


text:
Why does the F-16 have a fixed stabilizer section inboard of the stabilators?
So, we have a F-16 chilling on the ramp, showing us its tailfeathers:

Interestingly enough though, inboard of the all-flying stabilator sections, there is a fixed stabilizer section (this is quite clearly visible on the right due to what the stab is doing on that side).  This isn't universal on stabilator-equipped aircraft though, or even fighters, as the F-22 appears to have its all-flying horizontal tail hinged at the fuselage joints:

and the trimmable stabilizers on airliners are hinged at the fuselage-stabilizer joint as well:

So, why is it that the F-16 doesn't follow this pattern? Is there some aerodynamic design reason for that?

The F-16 has an all moving tail plane all right. What you are referring to as the 'fixed part' is actually the fuselage portion which houses the air brakes. It can be seen clearly in the following photograph.

Belgian AF stabilizer; image from designer.home.xs4all.nl

A-ha -- so there's a "glove" fuselage section there -- very not obivous if you're looking at the tailfeathers end from behind!


text:
How can I find the area situated under an airport traffic pattern?
For a given airport (general mix of traffic & runway setup/configuration), how can I determine/define which areas around the airport can expect to be situated under the traffic pattern for that airport?
(I'm asking because I'm working on some stuff related to urban planning in the vicinity of airports, and it seems that while instrument approach paths are well-defined due to the obstacle-free airspace zones they require, the size of the traffic pattern for any given runway isn't so well defined.  If there's something in the way airport noise studies or the likes are implemented I can point to to determine what areas are subject to noise/risks from aircraft in the VFR pattern, that would be quite appreciated!)

Maybe the urban plan can include a plan to notify people constructing and buying new houses about the pre-existing airport and proximity to it? One of the troubles in aviation is the continual push by newcomers to close preexisting airports, because the newcomers didn't do their homework and figured out there was airplane noise after deciding to buy a house, instead of before deciding (possibly, to not buy the house). It's enough of a recurring problem that the FAA tries to ban airpark-style housing at the edges of public airports.

@Azendale -- yeah, public notice is definitely a good thing for sure but the problem is that homebuyers already get a haystack of notices, which causes any given needle to get lost 90% of the time >.>

It turns out the FAA does define the traffic pattern airspace!
As it turns out, the traffic pattern airspace area is a well-defined entity, at least for US civil airports.  The FAA definition can be found in Figure 6-3-9 of FAA Order 7400.2, as reproduced below:

Generally speaking, the traffic pattern will be a box shape where one side is the runway itself, plus about one mile beyond each end; the parallel side will be about a mile from the runway, and there will be two connecting sides. This holds for the most common aircraft that fly a pattern around and around the airport, which are small single-engine propeller-driven trainers. Aircraft which are larger, or which have more engines, will fly larger patterns.
Someone recently posted on reddit about this website: ADS-B Exposed. It seems to be exactly what you're looking for: a heatmap of aircraft position reports, color-coded according to altitude. Zooming in, we can very easily see where aircraft are flying in the pattern around airports. For example, here is the Delaware, Ohio Municipal Airport (DLZ):

As an example of airports where jet aircraft fly traffic patterns, here is Vance Air Force Base (END). Note how there are differently-sized traffic patterns for each runway, smaller ones and larger ones, including the very large "radar patterns" in which aircraft are vectored for multiple practice instrument approaches.

+1 this website you have linked is a gem. Thank you!


text:
Aerobatics in "firm" IMC -- how would one do it?
Assuming you are aerobatically trained, IFR rated, have an aircraft that is rated for the aerobatic maneuvers you are planning to perform (let us assume that it is acrobatic category, even), and the aircraft in question is type certified and equipped for flight under IFR, how would you plan out and safely execute a set of aerobatic maneuvers in IMC (think solid cloud, but without serious up/downdrafts, icing, or lightning hazards) while flying under IFR?  Can you define a "box clearance" in an IFR flight plan, akin to a VFR aerobatic box, only defined by coordinates or intersections instead of ground reference points?  How feasible is it to carry out the Aresti catalog maneuvers by reference to flight instruments alone?

You can indeed ask for a block altitude and your clearance would be "block 14,000 to 16,000."

@rbp -- block altitudes I know about, but for acro in IMC, I'd want positive horizontal separation as well, which is why I asked about the "box clearance" -- the two would be used together to get a protected airspace volume to operate in.

Wave boxes in Class A airspace for gliders are defined via LOAs. Not sure you could get an IFR Acro box.

Wave box loa: http://www.seattleglidercouncil.org/SeattleGliderrev2003.pdf and http://www.seattleglidercouncil.org/gliderareamaps2009.pdf

I am interested to learn the answer to this question from someone with more aerobatic experience than me.  The ten or so hours of aerobatics that I've done have convinced me that attempting it without outside visual reference is not a feat I'd like to attempt.

What's the point of aerobatics if nobody can see you?

@raptortech97 -- I was thinking of this as something of  an "instrument mastery" exercise for an aerobatic pilot, if you will...

You could get a sector clearance. aka, you'd be cleared to operate between the ABC VOR's 090 to 140 radials from 50 to 80 DME, block altitude 4000 to 8000 or whatever you'd want to try.

I've heard at least one story of a fatality resulting from an attempt to loop in cloud, involved a P-38 during WW2 training.

When I was a student Naval Aviator in the TA-4J Skyhawk we would do a full acro series under the hood as a confidence maneuver.  (loop, aileron roll, barrel roll, half cuban eight, immelmann, and split S)

@MichaelHall -- you should expand on that, it sounds like answer material to me

It was done in VMC in a MOA, so I don't think it directly addresses the question.

No - you don't do it.
First and obvious reason, there's no body to see it.
Perhaps much more important is safety though. When pulling a loop, it's not like flight simulator where you just yank the stick aft and watch the attitude indicator (AI). An aerobatic pilot is constantly checking his attitude by looking at his wing tips, quickly glancing the left and right sides back and forth.
In fact, the AI is usually caged (meaning it is locked to prevent rotation) in such violent maneuver. The proper procedure is cage the AI, perform the maneuver, check straight and level (visually), then uncage the AI. If you don't, the gyroscope will tumble quite some time before it settles again, rendering it useless. Meaning, if you perform in IMC, you won't have accurate AI information for recovery.
For nearly vertical maneuvers (e.g. stall turn, rolling while vertical), even a functioning AI wouldn't help, since horizontal direction is undefined in this state. The AI and compass will just flip, yet you have no way to determine which way you go.
Violent G-forces also mean it is much more difficult to read instruments during such maneuver.

Would it be possible to do this if you had an attitude reference instrument that didn't need to be caged?

I guess fighter jets have it. I've never flown one though!

@kevin: I would expect most glass cockpits not to need caging as these use a set of (vibrating or laser) rate gyros and computer integration rather than free spinning gyro. Though apparently not all software is certified for it.

Aside: Look up gimbal lock on Apollo 11/13.

@JanHudec these guys had glass cockpit http://aviation-safety.net/database/record.php?id=20100214-0

@VladimirF, the fact that your AI works does not mean you are not going to loose spatial orientation and that extract does not say their AI tumbled.

@JanHudec I haven't said anything you are disproving. I pointed out that a glass cockpit does not save you.

@VladimirF, nothing can save you if you don't know what you are doing. But that is totally irrelevant here; the only question here is whether it provides correct attitude information when inverted or not.

@JanHudec In the linked full report you can read that according to the manufacturer, it will indicate correctly during a roll, but not during a loop. Or as kevin says when rolling when nearly vertical.

@VladimirF, hm, that's interesting. It also makes some sense; roll is definitely possible, but loop most likely isn't (the plane would likely stall or overspeed, depending on direction, before completing the loop at the maximum permitted G).

I've heard of at least one accident caused by a pilot trying to fly aerobatics in cloud.

authors: Vladimir F Героям слава


text:
KIBM RNAV (GPS) 10 -- did I find a charting error, or what is the TERPS rationale for this?
I was looking at the RNAV (GPS) approach to runway 10 at Kimball, NE (KIBM):

and was left wondering "How on earth could the straight-in visibility minima for approach categories C and D be lower than for approach categories A and B?"  Is this merely a charting error, or is there some strange clause in the TERPS that I'm not aware of that makes this possible?

Right now it could go either way. My best guess if it's not an error, there're protecting the slower(A&B) guys that could dive to the MDA quicker than the faster guys(C&D), for the obstructions near the approach. For the information, you'd have to hunt down the TERPS design guidlines, and I'm not sure where that is.

I'm staring at the TERPS tables for NPA visibility -- and they are where this anomaly comes from -- with the 314' HAT, table 3-5a in 8260.3B (the TERPS) calls out 7/8mi visibility, but is only allowed for Cats C and D -- Cats A and B use tables 3-6 and 3-7, which peg the visibility minimum at 1 mile for no approach lights and all HATs from 250' to 750'...but why?!

If you think it's an error, on the digital TERPS website under the FAQ, it does have a contact listed:
https://www.faa.gov/air_traffic/flight_info/aeronav/faq/#q6a

@slookabill -- it doesn't look to be a straightforward error as per the TERPS tables I cited; however, I'm still baffled as to why the tables are the way they are...

Without local altimeter Cat C/D leapfrogs A/B to be above 1. Interesting.

This is speculation, but in the absence of an obvious technical reason it's at least possible that this is because category C/D pilots have better lobbyists than category A/B ones.
I found an interesting but somewhat dated (1995) document  called Establishing Visibility Minimums; the author used to chair the ALPA TERPS committee. It says:

[The TERPS concepts] are a combination of science and politics, with a
  lot of undocumented historical precedence thrown in for good measure

And:

The political horse-trading that led to the 1976 [TERPS] revision [...]

In other words, we shouldn't necessarily assume that rules and regulations are entirely based on well-defined and documented technical criteria.
The (now outdated) 1976 chart in that document shows a default minimum of 1 mile visibility for all categories (with the single exception of an ILS with DH of 200', which is 3/4) or 1/2 with approach lighting, so a 7/8 minimum is a more recent change. So you could ask, why was this change made? One way would be to find the NPRM or other public records that detail the reasons for the change, but in practice it may be easier to contact the FAA directly and ask them (possibly under the FOIA if the information isn't already public).
One theoretical possibility is that the airline industry successfully lobbied to have 'their' minimums reduced in certain circumstances due to better training, equipment or whatever, and this approach is one of the affected ones. Diverting airline flights is enormously expensive, and the industry has a large incentive to make sure that as many instrument approaches succeed as possible. If lowering the minimums by 1/8 allows even a few flights a day to start an approach that would otherwise be illegal, that could add up to a huge financial saving.
But this is entirely guesswork on my part, I just wanted to make the point that sometimes we look for a technical explanation where the real reason is financial or political. For a definite answer, I would ask the FAA directly.

As UFO suggested in the comments above, the values come from the Tables in TERPS.
The reason why the visibility is greater for Category A and B is because in the typical "dive and drive" non-precision approach, the slower aircraft would descend to the MDA beyond 10,000ft from the landing threshold point, and therefore before the visual area of the approach. (TERPS Section 3.3.2)  Increasing the visibility requirement would allow the slower aircraft to see the airport environment from further away.

If that were the reason then wouldn't the cat A minimums always be greater than cat C?


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Is there a universal departure recovery procedure?
Let us say you're in a non-fly-by-wire tactical aircraft (say a F-15 or an A-4) doing maneuvers in the local MOA, and you manage to depart the jet in some non-spin fashion.  Is there a standard procedure for recovering the jet to controlled flight, analogous to how there are standard spin recovery procedures, or is the first step on the checklist "eject"?

A departure is simply an "exit from controlled flight", the appropriate recovery procedure depends on what kind of uncontrolled flight you are in. For example the recovery procedure for a spin is not the same as the procedure for an accelerated stall. I don't think there is any "universal" put this input in, get this result for recovering.

The only possibility that I can see is the pilot simply letting the aircraft "fly itself out", provided the aircraft has altitude and the flight surfaces have some authority. Aircraft are inherently stable in flight and many will recover by themselves (at least GA aircraft will), eventually.

The answer depends on the aircraft. In most cases it is No, but for some it is Yes.
The MiG-29 has a green button at the right side of the stick which recovers the aircraft to a wings-level, shallow climb attitude if pressed. Note that the MiG-29, unlike its Western counterparts, is aerodynamically stable over the full angle of attack range beyond 90° and the flight control system can recover the aircraft from any attitude, altitude and thrust permitting.
Here is a quote from someone reporting his experience of flying a Malaysian MiG-29 (link)

The stick has a red autopilot button on the left and a green auto
  recovery switch on the right for the disoriented pilot, and works by
  pressing the green panic button. The system recovers the jet to wings
  level and places the airplane in a slight climb if energy is
  available. This system is known to be reliable but is not often used.
  This is most likely due to the necessity of having to recognize that
  you are spatially disoriented prior to pushing the auto recovery
  button.

MiG-29 cockpit (picture source). The green button is clearly visible.

Ok, I think I have enough to answer this.
Here is an older training video I found on YouTube for ejection decisions. It looks like it has an aircraft from the A-10 "Family" of aircraft in it (I didn't watch the entire video, but looks like an older variant).
That all being said, a departure is not an automatic "eject" in any aircraft. Departure from controlled flight unless the aircraft is damaged or at a low altitude is typically recoverable, save for a few aircraft that cannot recover from certain departures (flat spins in some types for example).
As I said in my comment, there is no "universal procedure" for recovery. The recovery procedure differs depending on your flight attitude. Speaking from a GA perspective (but I assume it can somewhat be applied to military), recovering from a stall involves stick forward and power in, whereas recovering from a spin involves stick forward and power out (and other things).
The most "universal" method I can think of is to just let the airplane fly itself out. Airplanes (as I stated) are inherently stable in flight and provided you have the altitude and control surfaces have the authority, many types of departures will simply stabilize out and recover in time. Think of pilots in high-G maneuvers, even with G-Suits can sometimes black out (or red-out) for short periods. This is experienced quite a bit during some departures.
A good example of a pilot getting over anxious and bugging out is the Cornfield Bomber Incident where the aircraft recovered after the pilot ejected and continued flying into a field (and even ran along the ground for a long period of time afterwards).
So, to answer the question, the "first item" on the checklist is not "eject". I assume it would be a very short military (and flying) career for the pilot who ejected from a recoverable/flyable aircraft. Ejection seats are extremely effective even at low altitudes and pilots typically fly aircraft until they won't fly anymore, even if it only has one wing.

You referenced GA aircraft. The o.p. specified tactical a/c. I've read on aviation.se several times that fighter aircraft are inherently unstable. Some of them so much so that soon recovery is impossible without a parachute. I think some of the newer fbw ones have a just-let-go-of-the-stick recovery in the software but I doubt that applies to the ones he mentioned

I referenced GA for the recovery maneuver for stalls/spins only, but you are right, newer aircraft are becoming such that without complicated flight systems they are un-flyable aircraft. Older aircraft that the OP mentioned though (non-FBW) should be stable otherwise the pilot wouldn't have the skill to fly it, let alone do combat maneuvers.

And when I say "let go of the stick" I mean that the departure will stabilize, not that it will return to straight and level...

I think even the older fighters were still too unstable to self-recover. The cornfield incident was a rare occurrence. Afaik it was unrecoverable until the pilots ejected. Without their weight the center of gravity shifted and made it recover from the spin.


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How does the A320 FMGC (autothrust, autopilot) decide which radio altimeter readings to use?
How does the A320 (or other Airbus FBW aircraft, for that matter) decide which radio altimeter reading to use (say, for FMGC functions like autothrust), or whether to reject the radio altimeter data altogether and throw an ECAM to the pilots?  It's certainly not a full voting system, considering that the A320 only has two radio altimeters, not three...
(For the curious: I ask because the flight profile from the ACA 624 mishap bears some resemblance to what would happen if the power rolled back on very short final without the crew noticing.)

A320 auto-thrust does not roll back depending on altitude. It only cares about airspeed. AFAICT radio altitude is only used for setting ILS sensitivity and for flare during auto-land and since ACA624 was a non-precision approach (Halifax runway 5 does not have glide-slope), it shouldn't have had any effect.

@JanHudec -- got it, interesting that the Airbus A/T lacks a Flare mode (i.e. you have to pull the power back manually, albeit with an automatic callout for it) while the Boeing version has such a thing, even outside of autolands (you'd normally expect it to be the other way around).

@JanHudec -- make that an answer and I'll upvote it :)

@UnrecognizedFallingObject, please note Airbus has the flare mode in autoland(AP+Autothrust) thrust is automatically reduced irrespective of levers position. However autothrust alone in speed mode will require manual thrust reduction, otherwise after landing thrust is slightly increased automatically to maintain the approach speed.

First of all, RA1 is showed on the captain PFD and RA2 is showed on the F/O PFD. If one is detected as failed, the functional one is showed in both PFDs. This behavior is fixed, there is no way for the pilots to change it (instead, you can change the IR and ADR data with the relative knobs on the pedestal).
Now, two questions bring up:

How the system detects a failure in one RA if you have only 2 RAs and it cannot perform voting?

In this case, the only way to detect the failure is the self-detection, i.e. the control hardware and software specific to each RA performs the sanity checks. Since you cannot vote, there is no way to externally detect which one failed if they disagree (unless you cross-check with other data like database terrain or similar, but I doubt it does that). The disagreement triggers the ECAM message "NAV RA DEGRADED".

What the systems (GPWS, GLS, windshear, FWC, etc.) use if the two RAs disagree?

According to this Airbus document:

GPWS uses RA1
AP1/FD1 uses RA1
AP2/FD2 uses RA2

It doesn't state about other systems using RAs, probably they use only one side like GPWS and AP. At least these systems use RA information: reactive windshear, GLS autoland, TCAS, ROW, because in case of RA1+2 failure they are on the INOP SYS list. The FWC (Flight Warning Computer) is also using the RA signals to compute the flight phase (for example, to inhibit certain ECAM messages on takeoff and final). I can't find any information on FWC, it probably just disables message inhibition.
Differently it is in the A380, where you have 3 RAs, so they can vote, and all the systems use to the same value.


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If you file a flightplan with "NO SID", can you still get assigned a graphical ODP in your clearance?
Recently, the FAA has been moving to migrate Obstacle Departure Procedures from the textual form they are in in the A/FD Departure Procedures section to use the same graphical/charted format that SIDs use -- in addition, this means that charted SIDs are just a kind of charted Departure Procedure, just like charted Obstacle Departure Procedures.
However, when SIDs were originally implemented, there was a safety valve put in for pilots who weren't up for handling a complex departure procedure on their own -- you could file "NO SID" in your flight plan and ATC wouldn't assign you a SID as part of the clearance.  However, if the airport has a charted (graphical) Obstacle Departure Procedure and you're filing IFR, will you still get assigned the ODP as part of your clearance even if you are filing "NO SID" in your flight plan?  Or will ATC do something else instead?

ATC can indeed include an ODP in a clearance; this is from the ATC orders section 4-3-2:

Where an obstacle departure procedure (ODP) has been published for a
  location and pilot compliance is necessary to ensure separation,
  include the procedure as part of the ATC clearance.
EXAMPLE−
“Depart via the (airport name)(runway number) departure procedure.”
   Or
  “Depart via the (graphic ODP name) obstacle departure
  procedure.”

The "NO SID" note is exactly what it says, i.e. it applies to SIDs only. This is from the orders 4-3-3:

If a pilot does not wish to accept an ATC clearance to fly a SID,
  he/she is expected to advise ATC or state “NO SID” in his/her flight
  plan remarks.

Note that SIDs and ODPs exist for slightly different reasons: SIDs are primarily to simplify communication and automation; ODPs are specifically designed to help ensure obstacle clearance and you can fly one without an ATC clearance (unless ATC assigned some other departure procedure). That means it's usually in your interest to fly an ODP if possible.
Having said all that, a pilot can always decline some or all of a clearance that he isn't capable of flying or is just uncomfortable with. But if you reject both SIDs and ODPs, then ATC has to vector you and that could easily cause delays, especially at a busy airport.